The long-term objective of this research program is to enhance the effectiveness of treatments for patients with co-occurring alcohol use and posttraumatic stress disorders by advancing knowledge on models and mechanisms that explain the association [unreadable] between PTSD and alcohol use. Research has shown high comorbidity rates between PTSD and alcohol use disorders (AUDs) among clinical and community populations. The self-medication hypothesis has been proposed to explain the association between PTSD and alcohol use disorders. While prior research studies have identified patterns consistent with self-medication, they are limited by a reliance on static assessments of symptoms and alcohol use over long time intervals and retrospective reports. Given that self-medication may reflect a rapid unfolding of internal processes and behaviors over time, often within a day, tests of this hypothesis will require a methodology that can [unreadable] measure this potentially proximal interplay of symptom changes and alcohol use. Ecological momentary assessment is a methodology that can address questions about day-to-day process. [unreadable] [unreadable] The proposed study will focus on the following aims: (1) to establish the most effective methodology to study PTSD symptom reports and alcohol use among patients with alcohol use disorders; (2) to provide an initial test of the self-medication model wherein PTSD symptom exacerbation leads to increased alcohol use; and (3) to explore moderators of the association between PTSD symptoms and alcohol use, including patient gender. A total of 100 men and women discharged from alcohol use disorder [unreadable] treatment will receive cell phones that are connected to an Interactive Voice Response (IVR) system. This system will provide daily prompts to participants to report on PTSD symptoms, alcohol consumption, and drug use for 5 weeks following discharge. Participants will complete a 6-week in-person follow-up, wherein they will be asked about their experiences, perceptions, and satisfaction regarding the use of the cell phones and the study protocol. Based on the outcome of this preliminary study, the most effective methods for using this IVR protocol will be further refined and readied for [unreadable] larger-scale studies on PTSD and alcohol use disorder comorbidity etiology, with a focus on gender issues. [unreadable] [unreadable] [unreadable]